In the offshore oil and gas well art, it is frequently necessary to accomplish a task or tasks, by remote operations carried out from a platform or other operational base at the water surface, with relation to a device which has been installed in a location at, e.g., the floor of the body of water. With the depth of the installation beyond that range in which diver assistance is practical, such tasks are usually accomplished by use of a remotely operated handling tool lowered and manipulated by a handling string. In many cases, the device installed under water is of substantial size, so that provision for automatic grasping of the device by a handling tool is relatively uncomplicated, and since the device is frequently disposed well within the relatively large bore of, e.g., a wellhead body, location of the handling tool on landing of the tool is relatively simple and easy to achieve remotely with precision. See, for example, the tools disclosed in U.S. Pat. No. 3,240,511, issued Mar. 15, 1966, to Bishop et al for retrieving casing hangers, seal devices and the like. In other cases, as in cutting a guide line immediately adjacent the top of a guide post when the guide line has been broken, the problem of properly positioning the tool preparatory to cutting becomes more complex. See U.S. Pat. No. 3,709,291, issued Jan. 9, 1973, to Hanes et al. When the task to be accomplished involves removal of a device, such as a guide line bushing in a hollow guide post, more severe problems are presented, since the handling tool must extend within the post or other hollow member in order to engage the device on which the task is to be performed, and the bore in which the device is disposed is frequently of relatively small diameter and positioning of the handling tool must be accomplished with relative precision before being operated to engage the device.
While remotely operated handling tools of the type described are available to the trade, there has been a continuing need for improvement of such tools. On the one hand, there is a need for reducing the size, complexity and weight of the tool but, on the other hand, there is a need to achieve more precise location of the tool automatically as it is landed and greater certainty that the tool will perform in the intended fashion when responding to a remotely supplied control function.